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The activation of inert C–H bonds remains a challenge in current chemistry. Here, we report the excellent reactivity of the anionic gallylene species [LGa:][Na(THF)3] (L = [(2,6-iPr2C6H3)NC(CH3)]22−, 1) that allows the selective activation one ortho sp2 C–H bond of several azobenzene and azide derivatives at ambient temperature, with the transfer of the hydrogen atom to one of the nitrogen atoms. The process leads to the formation of the aryl amido products [LGa-κ2N,C-PhNN(H)(p-R-C6H3)][Na(solvent)3] (2, R = H solvent = DME (1,2-Dimethoxyethane); 3, R = –OMe, solvent = DME; 4, R = –NMe2 solvent = THF), [LGa-κ2N,C-(m-CH3-C6H4)NN(H)(m-CH3-C6H3)][Na(15-C-5)2] (5) with new Ga–C and Ga–N bonds. Moreover, 1 is also effective for the C–H activation of two azides RN3 (R = 2,4,6-Me3C6H2 or 2,6-iPr2C6H3), resulting in the formation of gallium amides [LGa(NH-2-(CH2)-4,6-Me2C6H2)][Na(15-C-5)2] (6) and [LGa(NH-2,6-iPr2C6H3)2][Na(THF)5] (7) through intra- or intermolecular sp3 C–H amination. Significantly, these reactions occur for the highly challenging activation of inert C(sp2)–H and C(sp3)–H bonds, thus demonstrating the excellent reactivity of the Ga(I) species 1. The products 2–7 were characterized by X-ray crystallography, 1H and 13C NMR, UV–vis spectroscopy, and density functional theory (DFT) calculations. [ABSTRACT FROM AUTHOR]

Among azobenzene derivatives, azothiophenes represent a relatively recent family of compounds that exhibit similar characteristics as dyes and photoreactive systems. Their technological applications are extensive thanks to the additional design flexibility conferred by the heteroaromatic ring. In this study, we present a comprehensive investigation of the structural and electronic properties of novel dyes derived from 3-thiophenamine, utilizing a multilevel approach. We thoroughly examined the potential energy surfaces of the E and Z isomers for three molecules, each bearing different substituents on the phenyl ring at the para position relative to the diazo group. This exploration was conducted through quantum chemistry calculations at various levels of theory, employing a continuum solvent model. Subsequently, we incorporated an explicit solvent (a dimethyl sulfoxide–water mixture) to simulate the most stable isomers using classical molecular dynamics, delivering a clear picture of the local solvation structure and intermolecular interactions. Finally, a hybrid quantum mechanics/molecular mechanics (QM/MM) approach was employed to accurately describe the evolution of the solutes' properties within their environment, accounting for finite temperature effects. [ABSTRACT FROM AUTHOR]

Azobenzene derivatives have become one of the most famous photoresponsive chromophores in the past few decades for their reversible molecular switches upon the irradiation of actinic light. To meet the ever-increasing requirements for applications in materials science, biomedicine, and light-driven devices, it is usually necessary to adjust their photochemical property from the molecular level by changing the substituents on the benzene rings of azobenzene groups. Among the diverse azobenzene derivatives, azopyridine combines the photoresponsive feature of azobenzene groups and the supramolecular function of pyridyl moieties in one molecule. This unique feature provides pH-responsiveness and hydrogen/halogen/coordination binding sites in the same chromophore, paving a new way to prepare multi-functional responsive materials through non-covalent interactions and reversible chemical reactions. This review summarizes the photochemical and photophysical properties of azopyridine derivatives in supramolecular states (e.g., hydrogen/halogen bonding, coordination interactions, and quaternization reactions) and illustrates their applications from photoresponsive liquid crystals to light-driven devices. We hope this review can highlight azopyridine as one more versatile candidate molecule for designing novel photoresponsive materials towards light-driven applications. [ABSTRACT FROM AUTHOR]

In the present study, photoirradiation molecularly imprinted polymer (MIP) with azobenzene was used as a functional monomer for the selective separation of the branched cyclodextrins. The functional monomer 4-methacryloyloxy azobenzene (MAA) and the molecular template 6-O-β-D-maltosyl-β-cyclodextrin (G2-β-CD) were implemented for the molecular imprinting. The core-shell structure of photoirradiation MIP was visualized by the transmission electron microscopy (TEM). With Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA), we identified that G2-β-CD was imprinted into the polymer and removed from the MIP. The binding association constant (Ka) and the maximum number of the binding site (Nmax) were 1.72 × 104 M-1 and 7.93 μmol·g-1 MIP, respectively. With alternate irradiation at 365 and 440 nm light, the prepared MIP reversibly released and rebound to the G2-β-CD, which resulted in the nearly zero amount of G2-β-CD in the solution. The HPLC results indicated that the purity of G2-β-CD could reach 90.8% after going through MIP. The main finding of our study was that the photoirradiation of MIP was an easy and effective method for the selective separation of the branched cyclodextrins. [ABSTRACT FROM AUTHOR]

New N-p-chloro-, N-p-bromo-, and N-p-nitrophenylazobenzylchitosan derivatives, as well as the corresponding azophenyl and azophenyl-p-sulfonic acids, were synthesized by coupling N-benzylvchitosan with aryl diazonium salts. The synthesized molecules were analyzed by UV-Vis, FT-IR, 1H-NMR and 15N-NMR spectroscopy. The capacity of copper chelation by these materials was studied by AAS. Chitosan and the derivatives were subjected to hydrolysis and the products were analyzed by ESI(+)-MS and GC-MS, confirming the formation of N-benzyl chitosan. Furthermore, the MS results indicate that a nucleophilic aromatic substitution (SnAr) reaction occurs under hydrolysis conditions, yielding chloroaniline from N-p-bromo-, and N-p-nitrophenylazo-benzylchitosan as well as bromoaniline from N-p-chloro-, and N-p-nitrophenylazobenzyl-chitosan. [ABSTRACT FROM AUTHOR]

The crystal structures of two azobenzene derivative Schiff base metal complexes (new C44H40CuN6O2 of P-1 and known C44H38MnN6O7 of P21/c abbreviated as Cu and Mn, respectively) were (re-)determined experimentally using conventional X-ray analysis to obtain electron density using a PLATON program. Cu affords a four-coordinated square planar geometry, while Mn affords a hexa-coordinated distorted octahedral geometry whose apical sites are occupied by an acetate ion and water ligands, which are associated with hydrogen bonds. The π-π or CH-π and hydrogen bonding intermolecular interactions were found in both crystals, which were also analyzed using a Hirshfeld surface analysis program. To compare these results with experimental results, a density functional theory (DFT) calculation was also carried out based on the crystal structures to obtain calculated electron density using a conventional Gaussian program. These results revealed that the axial Mn-O coordination bonds of Mn were relatively weaker than the in-plane M-N or M-O coordination bonds. [ABSTRACT FROM AUTHOR]